I had this issue too and was beyond frustrated. It turned out to be the simplest fix (which is usually the case in these situations). When you are on the "Pay Bills" screen, look below the "Set Credits" button, there is a "Payment" section. For me, the payment method in the drop-down list had somehow been changed to "Schedule Online Payment". Just change the method to "Check" and poof, I could apply my credit! This is the 4th forum about this issue that I've been on today looking for a solution, and NONE of them was any help... I hope this helps everyone else! I am also going to post this on the other 3 forums as well. Please respond and let me know if it doesn't work for you.